1. Field of the Invention
The present invention generally relates to waste heat recovery and, more particularly, is concerned with a water flow and heat exchange control system and method employed between a heat source, such as a central air conditioning system, and a water reservoir, such as a swimming pool.
2. Description of the Prior Art
In the past several decades, the use of air conditioning systems has become commonplace in both commercial and residential applications. Most home and small commercial air conditioning systems employ a closed vapor compression/expansion cycle with heat rejection to ambient air. Such systems include an evaporator portion with a refrigerant expansion valve, an evaporator, and an air circulation fan, and a condenser portion with a compressor, an air condenser, and an air condenser fan. Warm air is passed over the evaporator coil, where it is cooled by the transfer of heat to the liquid refrigerant flowing therethrough. The cooled air then passes to the interior of the building or other enclosure desired to be cooled. The refrigerant is converted to a vapor by absorbing the heat from the warm air. The vaporized refrigerant then flows to a compressor where it is compressed to a high pressure vapor, in the process of being heated to a temperature higher than the temperature of the available heat sink medium. The vapor then flows to the condenser, where it is condensed to a liquid by transfer of its sensible and latent heat to the heat sink medium, which is typically ambient air. The high pressure liquid then flows through a throttling device such as an expansion valve or capillary tube, where the pressure and temperature of the liquid are reduced to the conditions existing in the evaporator. In particular, the temperature of the liquid refrigerant is reduced to a point below the temperature of the air being cooled, thus completing the refrigerant cycle.
According to the basic thermodynamics of the vapor compression refrigeration cycle just described, the amount of energy required to operate the compressor is a function of the pressure and temperature of the refrigerant in the evaporator and the condenser. The condenser pressure and temperature are, in turn, dependent upon the temperature of the heat sink medium, typically ambient air. In general, the power consumed by the compressor is thus directly proportional to the temperature of the heat sink medium. Consequently, it is advantageous to utilize a low temperature heat sink medium where possbile to reduce the power consumption of the compressor. In larger commercial applications this is often accomplished by the use of cooling towers, wherein water is used to absorb the waste heat from the air conditioner and is subsequently evaporated to ambient air. The evaporation process effectively reduces the heat sink temperature of the air conditioner.
It may also be desirable to further conserve energy by recovering the heat rejected to the heat sink medium rather than rejecting the heat to the ambient air. It is well known in the art that the power consumption of an air conditioning system can be decreased by the use of a low temperature heat sink medium, while at the same time recovering the rejected heat for useful purposes. Systems utilizing swimming pool water as a heat sink medium, wherein the need for a swimming pool heater is reduced or eliminated by the simultaneous heating of the water, are disclosed in U.S. patents to Stiefel (U.S. Pat. No. 3,498,072), Webber (U.S. Pat. No. 3,926,008), Davies (U.S. Pat. No. 3,976,123), Babbitt et al (U.S. Pat. No. 4,232,529), Coombs (U.S. Pat. No. 4,238,933), Bottum (U.S. Pat. No. 4,383,419), Doctor (U.S. Pat. No. 4,667,479) and DeFazio (U.S. Pat. No. 4,907,418).
However, it has been perceived by the inventor herein that none of the systems of the aforementioned patents represent an optimum approach to rejected or waste heat recovery for maintaining a swimming pool at a desired temperature. For instance, none of the patents address the problem of how to properly regulate the flow of water through the heat exchanger interposed in the air conditioning system so as to correctly affect the heat rise of the water in the reservoir. Consequently, a need still exists for an improved approach to waste heat recovery for use in heating a swimming pool to and maintaining it at a desired temperature range.